code: function looksLikeLiteral(node) {
      return (node.type === "UnaryExpression" &&
          node.operator === "-" &&
          node.prefix &&
          node.argument.type === "Literal" &&
          typeof node.argument.value === "number");
  }
docs: Determines whether a non-Literal node is a negative number that should be
  treated as if it were a single Literal node.
  @param {ASTNode} node Node to test.
  @returns {boolean} True if the node is a negative number that looks like a
  real literal and should be treated as such.