text: from datetime import datetime
  import pytz
  
  
  def datetime_string_to_utc(datetime_string):
      """
      This function converts ISO 8601 time string with timezone info to a datetime object in UTC timezone.
      """
      tz_utc = pytz.utc
      try:
          dt = datetime.strptime(datetime_string, '%Y-%m-%dT%H:%M:%S%z')
      except ValueError:
          return None
      dt_utc = dt.astimezone(tz_utc)
      return dt_utc
  
  
  def datetime_string_to_naive(datetime_string):
      """
      This function converts ISO 8601 time string without timezone info to a naive datetime object.
      Main usage is for date of birth and other places where timezon is not required.
      """
      try:
          dt = datetime.strptime(datetime_string, '%Y-%m-%dT%H:%M:%S')
          return dt
      except ValueError:
          return None
  
  
  def datetime_string_to_datetime(datetime_string):
      """
      This function converts ISO 8601 time string with timezone info to a datetime object
      preserving the original timezone.
      """
      try:
          dt = datetime.strptime(datetime_string, '%Y-%m-%dT%H:%M:%S%z')
          return dt
      except ValueError:
          return None
  
  
  def convert_to_UTC(dt):
      """
      This function converts a datetime object with timezone information to a datetime object in UTC.
      """
      tz_utc = pytz.utc
      dt_utc = dt.astimezone(tz_utc)
      return dt_utc
  
  
  def dt_list_to_UTC_list(dt_list):
      """
      This function converts a list of datetime objects to a list of UTC datetime objects.
      """
      result = []
      for dt in dt_list:
          result.append(convert_to_UTC(dt))
      return result
  
  
  class Roles:
      """
      This class serves as the enum for roles.
      """
      EVERYBODY = 0
      STUDENT = 1
      PARENT = 2
      TEACHER = 4
      PRINCIPLE = 8
      ADMIN = 16
  
  
  class Relationship:
      FATHER = 1
      MOTHER = 2
      GRANDPA = 3
      GRANDMA = 4
      MOMGRANDPA = 5
      MOMGRANDMA = 6
      BROTHER = 7
      SISTER = 8
      UNCLE = 9
      AUNT = 10
      PARENT = 11
  
  
  class VALIDATIONS:
      WAITING = 0
      APPROVED = 1
      DENIED = 2
      REVOKED = 3
  
  
  class TRANSACTION_TYPE:
      DEBIT = -1
      CREDIT = 1