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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 from_sgf(sgfc):
 """Converts from an SGF coordinate to a Minigo coordinate."""

    if sgfc is None or sgfc == '' or (go.N <= 19 and sgfc == 'tt'):
        return None
    return _SGF_COLUMNS.index(sgfc[1]), _SGF_COLUMNS.index(sgfc[0])