function isMap(value) {
      return isObjectLike(value) && getTag(value) == mapTag;
    }
Checks if `value` is classified as a `Map` object.

@static
@memberOf _
@since 4.3.0
@category Lang
@param {*} value The value to check.
@returns {boolean} Returns `true` if `value` is correctly classified,
 else `false`.
@example

_.isMap(new Map);
// => true

_.isMap(new WeakMap);
// => false