Add is_series type guard, with tests

hyperglass/types.py

@@ -6,4 +6,4 @@ import typing as _t
 _S = _t.TypeVar("_S")
 
 Series = _t.Union[_t.MutableSequence[_S], _t.Tuple[_S], _t.Set[_S]]
-"""Like Sequence, but excludes `str`."""
+"""Like `typing.Sequence`, but excludes `str`."""

hyperglass/util/tests/test_typing.py

@@ -5,7 +5,7 @@
 import typing
 
 # Local
-from ..typing import is_type
+from ..typing import is_type, is_series
 
 
 class EmptyTestClass:
@@ -64,3 +64,14 @@ def test_is_type():
         result = is_type(value, _type)
         if result is not expected:
             raise AssertionError(f"Got `{value}`, expected `{str(_type)}`")
+
+
+def test_is_series():
+    checks = (
+        ((1, 2, 3), True),
+        ([1, 2, 3], True),
+        ("1,2,3", False),
+        ({1, 2, 3}, True),
+    )
+    for value, expected in checks:
+        assert is_series(value) is expected

hyperglass/util/typing.py

@@ -25,3 +25,10 @@ def is_type(value: typing.Any, *types: typing.Any) -> bool:
             return isinstance(value, type(_type))
         return isinstance(value, origin)
     return False
+
+
+def is_series(value: typing.Any) -> bool:
+    """Determine if a value is a `hyperglass.types.Series`, i.e. non-string `typing.Sequence`."""
+    if isinstance(value, (typing.MutableSequence, typing.Tuple, typing.Set)):
+        return True
+    return False