Added docstrings to fuctions for subsetting.
Added docstrings to fuctions for subsetting.

NCBI-Hackathons/Network_Stats_Acc_Interop,NCBI-Hackathons/Network_Stats_Acc_Interop,NCBI-Hackathons/Network_Stats_Acc_Interop,NCBI-Hackathons/Network_Stats_Acc_Interop