code: function getFunctionName (node) {
    if (node.type !== "CallExpression") {
      return null;
    }
    var callee = node.callee;
    if (callee && callee.type === "Identifier") {
      return callee.name;
    }
    return callee.property ? (callee.property.name || callee.property.value) : null;
  }
docs: Get function/method name from Call Expression
  Examples:
  "a()" - "a"
  "a.b()" - "b"
  "a.b.c()" - "c"
  
  @param {ASTNode} node
  @returns {?string}