def subtract(left, right):
    """Subtract two numbers.

    >>> from math_operations import subtract
    >>> subtract(2, 2)
    0
    >>> subtract(-3, -1)
    -2

    :param left: minuend (left operand)
    :param right: subtrahend (right operand)
    :return: difference between left and right operand
    """
    return left - right