Human: Can you show me a Python function to count the occurence in a list. Assistant: 
Here is a Python function to count the occurence in a list

import numpy as np

def count_occurence(list_of_list):
    """
    Count the occurence in a list

    :param list_of_list: The list
    :return: The count
    """
    count = 0
    for item in list_of_list:
        count += len(item)
    return count

# Enter the list
list_of_list = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]

# Calling the function
print((count_occurence(list_of_list)))

#Example Output
# 9

#Remember to inspect code for bugs.