dist/flow.js
function extend(dst, src) {
    each(arguments, function(obj) {
      if (obj !== dst) {
        each(obj, function(value, key){
          dst[key] = value;
        });
      }
    });
    return dst;
  }
function extend(dst, src) {
    each(arguments, function(obj) {
      if (obj !== dst) {
        each(obj, function(value, key){
          dst[key] = value;
        });
      }
    });
    return dst;
  }
Extends the destination object `dst` by copying all of the properties from
the `src` object(s) to `dst`. You can specify multiple `src` objects.
@function
@param {Object} dst Destination object.
@param {...Object} src Source object(s).
@returns {Object} Reference to `dst`.