Reference: isEven

isEven(x) returns True if x is even, and False otherwise. x is any integer.

Examples: isEven(5) = False
          isEven(10) = True

isEven(expr, var, domain) returns True if the expression expr in the single variable var restricted to the domain domain is an even function, and False otherwise.

Examples: isEven("sin(x)", "x", [0, 10, 0.1]) = False
          isEven("x⋅sin(x)", "x", [0, 10, 0.1]) = True