Write a function to concatenate two dictionaries to create a new one.

Write a function that takes two dictionaries as its input and returns a dictionary after concatenating them.

Example:

Input:

    {1: 10, 2: 20}, {3: 30, 4: 40}

Output:

    {1: 10, 2: 20, 3: 30, 4: 40}

Note:

  • Avoid using nested for loops.