code: function(m1, m2, fship, data) {
      fship.added = new Date();
      fship.data = data;
  
      return this.findOneAndUpdate({ _id: m1 }, {
        $push: {
          [pathName]: fship,
        },
      }, { new: false })
        .then(() => fship);
    }
docs: Create friendship
  
  @returns a function to create a new friendship between two parties
  @api private