Function check_ops_is_prefix 

fn check_ops_is_prefix(
    psess: &ParseSess,
    node_id: NodeId,
    macros: &Stack<'_, MacroState<'_>>,
    binders: &FxHashMap<MacroRulesNormalizedIdent, BinderInfo>,
    ops: &Stack<'_, KleeneToken>,
    span: Span,
    name: MacroRulesNormalizedIdent,
)

Checks that a meta-variable occurrence is valid.

Arguments:

• psess is used to emit diagnostics and lints
• node_id is used to emit lints
• macros is the stack of possible outer macros
• binders contains the binders of the associated LHS
• ops is the stack of Kleene operators from the RHS
• span is the span of the meta-variable to check
• name is the name of the meta-variable to check