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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 write_src(hdf5_out, gctoo_object, out_file_name):
 """ 	Writes src as attribute of gctx out file. 	Input: 		- hdf5_out (h5py):
 hdf5 file to write to 		- gctoo_object (GCToo):
 GCToo instance to be written to .gctx 		- out_file_name (str):
 name of hdf5 out file. 	"""

    if gctoo_object.src == None:
        hdf5_out.attrs[src_attr] = out_file_name
    else:
        hdf5_out.attrs[src_attr] = gctoo_object.src