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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def validate_root_vertex_directives(root_ast):
 """Validate the directives that appear at the root vertex field."""

    directives_present_at_root = set()
    for directive_obj in root_ast.directives:
        directive_name = directive_obj.name.value

        if is_filter_with_outer_scope_vertex_field_operator(directive_obj):
            raise GraphQLCompilationError(u'Found a filter directive with an operator that is not'
                                          u'allowed on the root vertex: {}'.format(directive_obj))

        directives_present_at_root.add(directive_name)

    disallowed_directives = directives_present_at_root & VERTEX_DIRECTIVES_PROHIBITED_ON_ROOT
    if disallowed_directives:
        raise GraphQLCompilationError(u'Found prohibited directives on root vertex: '
                                      u'{}'.format(disallowed_directives))