Check type variable values [type-var]

Mypy checks that value of a type variable is compatible with a valuerestriction or the upper bound type.

Example:

from typing import TypeVar
 
T1 = TypeVar('T1', int, float)
 
def add(x: T1, y: T1) -> T1:
    return x + y
 
add(4, 5.5)  # OK
 
# Error: Value of type variable "T1" of "add" cannot be "str"  [type-var]
add('x', 'y')