samuelcolvin
diff --git a/.codecov.yml b/.codecov.yml
@@ -0,0 +1,6 @@
+coverage:
+  precision: 2
+  range: [95, 100]
+
+comment:
+  layout: 'header, diff, flags, files, footer'
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
@@ -43,9 +43,11 @@ jobs:
         make check-dist
 
     - name: test with extras
-      run: make test
+      run: |
+        make test
+        coverage xml
 
-    - uses: codecov/codecov-action@v1
+    - uses: codecov/codecov-action@v1.0.7
       with:
         file: ./coverage.xml
         env_vars: EXTRAS,PYTHON,OS
@@ -58,10 +60,10 @@ jobs:
         make test
         coverage xml
 
-    - uses: codecov/codecov-action@v1
+    - uses: codecov/codecov-action@v1.0.7
       with:
         file: ./coverage.xml
-        env_vars: DEPS,PYTHON,OS
+        env_vars: EXTRAS,PYTHON,OS
       env:
         EXTRAS: no
 

diff --git a/devtools/ansi.py b/devtools/ansi.py
@@ -1,24 +1,20 @@
-import re
-import sys
 from enum import IntEnum
-from typing import Any
+
+from .utils import isatty
 
 _ansi_template = '\033[{}m'
-_ansi_re = re.compile('\033\\[((?:\\d|;)*)([a-zA-Z])')
 
 __all__ = 'sformat', 'sprint'
 
-
-def isatty(stream=None):
-    stream = stream or sys.stdout
-    try:
-        return stream.isatty()
-    except Exception:
-        return False
+MYPY = False
+if MYPY:
+    from typing import Any
 
 
 def strip_ansi(value):
-    return _ansi_re.sub('', value)
+    import re
+
+    return re.sub('\033\\[((?:\\d|;)*)([a-zA-Z])', '', value)
 
 
 class Style(IntEnum):
@@ -68,7 +64,7 @@ class Style(IntEnum):
     # this is a meta value used for the "Style" instance which is the "style" function
     function = -1
 
-    def __call__(self, input: Any, *styles, reset: bool = True, apply: bool = True):
+    def __call__(self, input: 'Any', *styles: 'Style', reset: bool = True, apply: bool = True) -> str:
         """
         Styles text with ANSI styles and returns the new string.
 

diff --git a/devtools/debug.py b/devtools/debug.py
@@ -1,20 +1,17 @@
-import ast
-import dis
-import inspect
 import os
-import pdb
 import sys
-from pathlib import Path
-from textwrap import dedent, indent
-from types import FrameType
-from typing import Generator, List, Optional, Tuple
 
-from .ansi import isatty, sformat
+from .ansi import sformat
 from .prettier import PrettyFormat, env_true
 from .timer import Timer
+from .utils import isatty
 
 __all__ = 'Debug', 'debug'
-CWD = Path('.').resolve()
+MYPY = False
+if MYPY:
+    import ast
+    from types import FrameType
+    from typing import Generator, List, Optional, Tuple
 
 
 pformat = PrettyFormat(
@@ -78,7 +75,7 @@ class DebugOutput:
     arg_class = DebugArgument
     __slots__ = 'filename', 'lineno', 'frame', 'arguments', 'warning'
 
-    def __init__(self, *, filename: str, lineno: int, frame: str, arguments: List[DebugArgument], warning=None):
+    def __init__(self, *, filename: str, lineno: int, frame: str, arguments: 'List[DebugArgument]', warning=None):
         self.filename = filename
         self.lineno = lineno
         self.frame = frame
@@ -110,22 +107,9 @@ def __repr__(self) -> str:
 
 class Debug:
     output_class = DebugOutput
-    complex_nodes = (
-        ast.Call,
-        ast.Attribute,
-        ast.Subscript,
-        ast.IfExp,
-        ast.BoolOp,
-        ast.BinOp,
-        ast.Compare,
-        ast.DictComp,
-        ast.ListComp,
-        ast.SetComp,
-        ast.GeneratorExp,
-    )
 
     def __init__(
-        self, *, warnings: Optional[bool] = None, highlight: Optional[bool] = None, frame_context_length: int = 50
+        self, *, warnings: 'Optional[bool]' = None, highlight: 'Optional[bool]' = None, frame_context_length: int = 50
     ):
         self._show_warnings = self._env_bool(warnings, 'PY_DEVTOOLS_WARNINGS', True)
         self._highlight = self._env_bool(highlight, 'PY_DEVTOOLS_HIGHLIGHT', None)
@@ -149,6 +133,8 @@ def format(self, *args, **kwargs) -> DebugOutput:
         return self._process(args, kwargs, 'format')
 
     def breakpoint(self):
+        import pdb
+
         pdb.Pdb(skip=['devtools.*']).set_trace()
 
     def timer(self, name=None, *, verbose=True, file=None, dp=3) -> Timer:
@@ -160,7 +146,7 @@ def _process(self, args, kwargs, func_name: str) -> DebugOutput:
         """
         # HELP: any errors other than ValueError from _getframe? If so please submit an issue
         try:
-            call_frame: FrameType = sys._getframe(2)
+            call_frame: 'FrameType' = sys._getframe(2)
         except ValueError:
             # "If [ValueError] is deeper than the call stack, ValueError is raised"
             return self.output_class(
@@ -175,15 +161,20 @@ def _process(self, args, kwargs, func_name: str) -> DebugOutput:
         function = call_frame.f_code.co_name
         if filename.startswith('/'):
             # make the path relative
+            from pathlib import Path
+
+            cwd = Path('.').resolve()
             try:
-                filename = str(Path(filename).relative_to(CWD))
+                filename = str(Path(filename).relative_to(cwd))
             except ValueError:
                 # happens if filename path is not within CWD
                 pass
 
         lineno = call_frame.f_lineno
         warning = None
 
+        import inspect
+
         try:
             file_lines, _ = inspect.findsource(call_frame)
         except OSError:
@@ -214,7 +205,23 @@ def _args_inspection_failed(self, args, kwargs):
         for name, value in kwargs.items():
             yield self.output_class.arg_class(value, name=name)
 
-    def _process_args(self, func_ast, code_lines, args, kwargs) -> Generator[DebugArgument, None, None]:  # noqa: C901
+    def _process_args(self, func_ast, code_lines, args, kwargs) -> 'Generator[DebugArgument, None, None]':  # noqa: C901
+        import ast
+
+        complex_nodes = (
+            ast.Call,
+            ast.Attribute,
+            ast.Subscript,
+            ast.IfExp,
+            ast.BoolOp,
+            ast.BinOp,
+            ast.Compare,
+            ast.DictComp,
+            ast.ListComp,
+            ast.SetComp,
+            ast.GeneratorExp,
+        )
+
         arg_offsets = list(self._get_offsets(func_ast))
         for i, arg in enumerate(args):
             try:
@@ -226,7 +233,7 @@ def _process_args(self, func_ast, code_lines, args, kwargs) -> Generator[DebugAr
 
             if isinstance(ast_node, ast.Name):
                 yield self.output_class.arg_class(arg, name=ast_node.id)
-            elif isinstance(ast_node, self.complex_nodes):
+            elif isinstance(ast_node, complex_nodes):
                 # TODO replace this hack with astor when it get's round to a new release
                 start_line, start_col = arg_offsets[i]
 
@@ -252,12 +259,14 @@ def _process_args(self, func_ast, code_lines, args, kwargs) -> Generator[DebugAr
             yield self.output_class.arg_class(value, name=name, variable=kw_arg_names.get(name))
 
     def _parse_code(
-        self, filename: str, file_lines: List[str], first_line: int, last_line: int
-    ) -> Tuple[ast.AST, List[str]]:
+        self, filename: str, file_lines: 'List[str]', first_line: int, last_line: int
+    ) -> 'Tuple[ast.AST, List[str]]':
         """
         All we're trying to do here is build an AST of the function call statement. However numerous ugly interfaces,
         lack on introspection support and changes between python versions make this extremely hard.
         """
+        from textwrap import dedent
+        import ast
 
         def get_code(_last_line: int) -> str:
             lines = file_lines[first_line - 1 : _last_line]
@@ -295,10 +304,12 @@ def get_code(_last_line: int) -> str:
         return func_ast, code_lines
 
     @staticmethod  # noqa: C901
-    def _statement_range(call_frame: FrameType, func_name: str) -> Tuple[int, int]:  # noqa: C901
+    def _statement_range(call_frame: 'FrameType', func_name: str) -> 'Tuple[int, int]':  # noqa: C901
         """
         Try to find the start and end of a frame statement.
         """
+        import dis
+
         # dis.disassemble(call_frame.f_code, call_frame.f_lasti)
         # pprint([i for i in dis.get_instructions(call_frame.f_code)])
 
@@ -343,15 +354,20 @@ def _statement_range(call_frame: FrameType, func_name: str) -> Tuple[int, int]:
         return first_line, last_line
 
     @staticmethod
-    def _wrap_parse(code, filename):
+    def _wrap_parse(code: str, filename: str) -> 'ast.Call':
         """
         async wrapper is required to avoid await calls raising a SyntaxError
         """
+        import ast
+        from textwrap import indent
+
         code = 'async def wrapper():\n' + indent(code, ' ')
         return ast.parse(code, filename=filename).body[0].body[0].value
 
     @staticmethod
     def _get_offsets(func_ast):
+        import ast
+
         for arg in func_ast.args:
             start_line, start_col = arg.lineno - 2, arg.col_offset - 1