Returns the local part of the name of $arg as an xs:string
            that is either the zero-length string, or has the lexical form of an
               xs:NCName.
fn:local-name( xs:stringfn:local-name( $arg as node()?xs:stringIf the argument is omitted, it defaults to the context item (.). The
            behavior of the function if the argument is omitted is exactly the same as if the
            context item had been passed as the argument.
If the argument is supplied and is the empty sequence, the function returns the zero-length string.
If the node identified by $arg has no name (that is, if it is a document
            node, a comment, a text node, or a namespace node having no name), the function returns
            the zero-length string.
Otherwise, the function returns the local part of the expanded-QName of the node
            identified by $arg, as determined by the dm:node-name accessor
            defined in ). This will be an
               xs:string whose lexical form is an xs:NCName.
The following errors may be raised when $arg is omitted:
If the context item is absent, dynamic error
If the context item is not a node, type error .