delimited strings to dictionary. good for flexibly ingesting key value pairs

kwargs.py

def kwargs(string, separator='=', type=None):
    """Return a dict from a delimited string.
    
    If 'type' is not None, values will be passed through
    to type before returning the dictionary.
    """
    if separator not in string:
        raise ValueError("Separator '%s' not in value '%s'"
                         % (separator, string))
    if string.strip().startswith(separator):
        raise ValueError("Value '%s' starts with separator '%s'"
                         % (string, separator))

    kvps = {}
    split = string.split(separator)
    pairs = [split[0+i:2+i] for i in range(0, len(split)-1, 1)]
    for i, (tkey, tvalue) in enumerate(pairs):
        key = tkey.strip()
        if i != 0:
            key = key[key.rindex(' '):].strip()
        value = tvalue.strip()
        if i != (len(pairs) - 1):
            value = value[:value.rindex(' ')].strip()
        if key in kvps:
            raise ValueError("Specified value for '%s' twice" % key)
        if not value:
            raise ValueError("No value for key '%s'" % key)
        kvps[key] = value
    if type is not None:
        kvps = {k: type(v) for k, v in kvps.items()}
    return kvps