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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 parse (cls, line, lineno, log, cmddict=None):
 """Parses the SeqMetaCmd from a line of text. Warning and error messages are logged via the SeqMsgLog log. """

    start  = line.find('%')
    pos    = SeqPos(line, lineno, start + 1, len(line))
    result = None

    if start >= 0:
      result = cls(line[start:], pos)

    return result