private void resolveMappingKey(PsiElement problemTarget, PyStringLiteralExpression key, PyExpression value) {
        final String name = key.getStringValue();
        if (myUsedMappingKeys.get(name) != null) {
          myUsedMappingKeys.put(name, true);
          if (value != null) {
            checkExpressionType(value, myFormatSpec.get(name), problemTarget);
          }
        }
      }
private void resolveMappingKey(PsiElement problemTarget, PyStringLiteralExpression key, PyExpression value)