
    Write a function that validates delivery route identifiers by checking if they follow the company's standard naming convention of lowercase letters connected by underscores. The function should return true for valid route identifiers like "north_route_b" or "downtown_express" and false for any identifiers that don't follow this format, ensuring consistency across the fleet management system.
    

    
import re

def text_lowercase_underscore(text):
    """
    Write a function that validates delivery route identifiers by checking if they follow the company's standard naming convention of lowercase letters connected by underscores. The function should return true for valid route identifiers like "north_route_b" or "downtown_express" and false for any identifiers that don't follow this format, ensuring consistency across the fleet management system.
    

    """
import re

def text_lowercase_underscore(text):
    """
    Write a function that validates delivery route identifiers by checking if they follow the company's standard naming convention of lowercase letters connected by underscores. The function should return true for valid route identifiers like "north_route_b" or "downtown_express" and false for any identifiers that don't follow this format, ensuring consistency across the fleet management system.
    

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