Fixed doctest for xy_of_node.
Fixed doctest for xy_of_node.

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