
    Write a function that validates bus route identifiers in the transportation network database by checking if they follow the standardized naming convention of lowercase letters connected by underscores. The function should return true if the route identifier is properly formatted (like "north_terminal_express"), and false otherwise.
    

    
import re

def text_lowercase_underscore(text):
    """
    Write a function that validates bus route identifiers in the transportation network database by checking if they follow the standardized naming convention of lowercase letters connected by underscores. The function should return true if the route identifier is properly formatted (like "north_terminal_express"), and false otherwise.
    

    """
import re

def text_lowercase_underscore(text):
    """
    Write a function that validates bus route identifiers in the transportation network database by checking if they follow the standardized naming convention of lowercase letters connected by underscores. The function should return true if the route identifier is properly formatted (like "north_terminal_express"), and false otherwise.
    

    """
    patterns = '^[a-z]+_[a-z]+$'
    if re.search(patterns, text):
        return True
    else:
        return False