Resolves the argName argument (default 'envir', pmatch against allParamNames), falling back to positionalFallbackIndex, to an EnvirResolution.
argName
'envir'
allParamNames
positionalFallbackIndex
Optional
Resolves the
argNameargument (default'envir', pmatch againstallParamNames), falling back topositionalFallbackIndex, to an EnvirResolution.