import re


def tamper(payload, **kwargs):
    """
    Splits FROM schema identifiers (e.g. 'testdb.users') with whitespace (e.g. 'testdb 9.e.users')

    Requirement:
        * MySQL

    Notes:
        * Reference: https://media.blackhat.com/us-13/US-13-Salgado-SQLi-Optimization-and-Obfuscation-Techniques-Slides.pdf

    >>> tamper('SELECT id FROM testdb.users')
    'SELECT id FROM testdb 9.e.users'
    """

    return re.sub(r"(?i)( FROM \w+)\.(\w+)", r"\g<1> 9.e.\g<2>", payload) if payload else payload