code: func (c *Call) merge(r *Call) Call {
  	return Call{
  		SrcPath:      c.SrcPath,
  		Line:         c.Line,
  		Func:         c.Func,
  		Args:         c.Args.merge(&r.Args),
  		LocalSrcPath: c.LocalSrcPath,
  		IsStdlib:     c.IsStdlib,
  	}
  }
docs: // merge merges two similar Call, zapping out differences.