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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 _capture_variable(iterator, parameters):
 """ return the replacement string. this assumes the preceeding {{ has already been popped off. """

    key = ""
    next_c = next(iterator)
    while next_c != "}":
        key += next_c
        next_c = next(iterator)
    # remove the final "}"
    next(iterator)
    return parameters[key]