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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 thresholdForIdentity(identity, colors):
 """ Get the best identity threshold for a specific identity value. @param identity: A C{float} nucleotide identity. @param colors: A C{list} of (threshold, color) tuples, where threshold is a C{float} and color is a C{str} to be used as a cell background. This is as returned by C{parseColors}. @return: The first C{float} threshold that the given identity is at least as big as. """

    for threshold, _ in colors:
        if identity >= threshold:
            return threshold
    raise ValueError('This should never happen! Last threshold is not 0.0?')