<human>:  add update merge comncatentate two dictionaries.
<bot>: Here is a Python function to add update merge to combine two dictionaries

# Enter the first dictionary
dict1 = {'key1': 'value1', 'key2': 'value2'}

# Enter the second dictionary
dict2 = {'key3': 'value3', 'key4': 'value4'}

# Calling the function
print((dict_union(dict1, dict2)))

#Example Output
# {'key1': 'value1', 'key2': 'value2', 'key3': 'value3', 'key4': 'value4'}

#Remember to inspect code for bugs.