Function parse_ltl_atom 

fn parse_ltl_atom<T>(
    pair: Pair<'_, Rule>,
    builder: &T,
    ctx: &TLAParsingContext<'_>,
) -> Result<ELTLExpression, Box<Error<()>>>
where
    T: IsDeclared<Variable> + IsDeclared<Location> + IsDeclared<Parameter>,

Parse an ltl atom into a single ltl expression

This function parses an ltl atom and returns the corresponding ltl expression. The function returns an error if the expression refers to an unknown location.