instance check for ABC real seems to be slow. See if removing that im…

…proves performance.

uncertainties/core.py

@@ -16,7 +16,6 @@
 
 from builtins import str, zip, range, object
 from math import isnan, sqrt  # Optimization: no attribute look-up
-from numbers import Real
 from typing import Optional, Union
 
 from uncertainties.formatting import format_ufloat
@@ -286,7 +285,7 @@ class UFloat(object):
     def __init__(
         self,
         nominal_value: float,
-        uncertainty: Union[UCombo, Real],
+        uncertainty: Union[UCombo, float],
         tag: Optional[str] = None,
     ):
         """
@@ -302,7 +301,7 @@ def __init__(
         float such that a new UCombo and UAtom is generated.
         """
         self._nominal_value = float(nominal_value)
-        if isinstance(uncertainty, Real):
+        if isinstance(uncertainty, float):
             if not isnan(uncertainty) and uncertainty < 0:
                 raise NegativeStdDev("The standard deviation cannot be negative")
             if uncertainty == 0:

uncertainties/ucombo.py

@@ -2,7 +2,6 @@
 
 from collections import defaultdict
 from math import sqrt
-from numbers import Real
 from typing import Optional, Tuple, Union
 import uuid
 
@@ -92,14 +91,14 @@ def __add__(self: UCombo, other) -> UCombo:
     def __radd__(self: UCombo, other: UCombo) -> UCombo:
         return self.__add__(other)
 
-    def __mul__(self: UCombo, scalar: Real) -> UCombo:
-        if not isinstance(scalar, Real):
+    def __mul__(self: UCombo, scalar: float) -> UCombo:
+        if not isinstance(scalar, float):
             return NotImplemented
         if scalar == 0 or not self:
             return UCombo(())
         return UCombo(((self, float(scalar)),))
 
-    def __rmul__(self: UCombo, scalar: Real) -> UCombo:
+    def __rmul__(self: UCombo, scalar: float) -> UCombo:
         return self.__mul__(scalar)
 
     def __iter__(self: UCombo):