@staticmethod
def is_a_number(value):
    """Return True if value is an int, a float or a string representation of a number."""
    if type(value) in (int, float):
        return True
    if not isinstance(value, str):
        return False
    if value.isnumeric():
        return True
    try:
        float(value)
        return True
    except ValueError:
        return False
