Added docstrings.
Added docstrings.

cmshobe/landlab,laijingtao/landlab,landlab/landlab,cmshobe/landlab,Carralex/landlab,SiccarPoint/landlab,amandersillinois/landlab,csherwood-usgs/landlab,laijingtao/landlab,ManuSchmi88/landlab,landlab/landlab,ManuSchmi88/landlab,SiccarPoint/landlab,RondaStrauch/landlab,RondaStrauch/landlab,csherwood-usgs/landlab,Carralex/landlab,landlab/landlab,RondaStrauch/landlab,cmshobe/landlab,Carralex/landlab,ManuSchmi88/landlab,amandersillinois/landlab