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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 get_unchanged(src_list, npred_dict_new, npred_dict_old, npred_threshold=1e4, frac_threshold=0.9):
 """Compare two dictionarys of npreds, and get the list of sources than have changed less that set thresholds Parameters src_list : list List of sources to examine npred_dict_new : dict Dictionary mapping source name to npred for the current weights file npred_dict_old : dict Dictionary mapping source name to npred for the previous weights file npred_threshold : float Minimum value of npred above which to consider sources changed frac_threshold : float Value of npred_old / npred_new above which to consider sources unchanged Returns ------- l : list Names of 'unchanged' sources """

    o = []
    for s in src_list:
        npred_new = npred_dict_new[s]
        if npred_new < npred_threshold:
            o += [s]
            continue
        if npred_dict_old is None:
            npred_old = 0.
        else:
            npred_old = npred_dict_old[s]
        frac = npred_old / npred_new
        if frac > frac_threshold:
            o += [s]
    return o