
    Develop a function to process raw sensor data from transit vehicles by removing non-critical maintenance codes (represented by lowercase characters) from the data stream, leaving only critical maintenance alerts (uppercase characters) for immediate attention by maintenance teams. The function should analyze the input string containing mixed-case maintenance codes and status indicators, filtering out all lowercase substrings while preserving the uppercase alert codes in their original sequence.
    

    
import re

def remove_lowercase(str1):
    """
    Develop a function to process raw sensor data from transit vehicles by removing non-critical maintenance codes (represented by lowercase characters) from the data stream, leaving only critical maintenance alerts (uppercase characters) for immediate attention by maintenance teams. The function should analyze the input string containing mixed-case maintenance codes and status indicators, filtering out all lowercase substrings while preserving the uppercase alert codes in their original sequence.
    

    """
import re

def remove_lowercase(str1):
    """
    Develop a function to process raw sensor data from transit vehicles by removing non-critical maintenance codes (represented by lowercase characters) from the data stream, leaving only critical maintenance alerts (uppercase characters) for immediate attention by maintenance teams. The function should analyze the input string containing mixed-case maintenance codes and status indicators, filtering out all lowercase substrings while preserving the uppercase alert codes in their original sequence.
    

    """
    return re.sub('[a-z]', '', str1)