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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:

def _extract_key_val(kv, delimiter='='):
    '''Extract key and value from key=val string.

    Example:
    >>> _extract_key_val('foo=bar')
    ('foo', 'bar')
    '''
    pieces = kv.split(delimiter)
    key = pieces[0]
    val = delimiter.join(pieces[1:])
    return key, val