Fixed doctest set_nodata_nodes_to_fixed_gradient.
Fixed doctest set_nodata_nodes_to_fixed_gradient.

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