Function interp_lock_binding 

fn interp_lock_binding(
    positional: &[RValue],
    _named: &[(String, RValue)],
    _context: &BuiltinContext<'_>,
) -> Result<RValue, RError>

Lock a specific binding in an environment.

@param sym name of the binding to lock (character string) @param env environment containing the binding @return NULL (invisibly)