Function checkNote13

SPARQL 1.2 version of the SPARQL 1.1 checkNote13, named after it so it overrides it in the validation export. Grammar note 12 of https://www.w3.org/TR/sparql12-query/#sparqlGrammar (note 13 in SPARQL 1.1)

The variable assigned in a BIND clause must not already be in-use within the immediately preceding TriplesBlock within a GroupGraphPattern. See also https://www.w3.org/TR/sparql12-query/#variableScope In BIND (expr AS v) requires that the variable v is not in-scope from the preceeding elements in the group graph pattern in which it is used. The in-scope variables include those of the preceding TriplesBlock, also those within triple terms, reifiers, and annotations.