<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def count_sources_in_cluster(n_src, cdict, rev_dict):
 """ Make a vector of sources in each cluster Parameters n_src : number of sources cdict : dict(int:[int,]) A dictionary of clusters. Each cluster is a source index and the list of other source in the cluster. rev_dict : dict(int:int) A single valued dictionary pointing from source index to cluster key for each source in a cluster. Note that the key does not point to itself. Returns `np.ndarray((n_src),int)' with the number of in the cluster a given source belongs to. """

    ret_val = np.zeros((n_src), int)
    for i in range(n_src):
        try:
            key = rev_dict[i]
        except KeyError:
            key = i
        try:
            n = len(cdict[key])
        except:
            n = 0
        ret_val[i] = n
    return ret_val