'Compare data read from file with self.value if operator is \'=\'.
:param data: Data read from the file.
:return: None if no match between data and expected value string. Else,
print matching mime type information.'

def test(self, data):

    if self.mask:
        data = (data & self.mask)
    if (self.op == '='):
        if (self.value == data):
            return self.msg
    elif (self.op == '<'):
        pass
    elif (self.op == '>'):
        pass
    elif (self.op == '&'):
        pass
    elif (self.op == '^'):
        pass
    return None
