docs: def configure_environ(dsn_env_name='PROM_DSN', connection_class=DsnConnection):
      """
      configure interfaces based on environment variables
  
      by default, when prom is imported, it will look for PROM_DSN, and PROM_DSN_N (where
      N is 1 through infinity) in the environment, if it finds them, it will assume they
      are dsn urls that prom understands and will configure db connections with them. If you
      don't want this behavior (ie, you want to configure prom manually) then just make sure
      you don't have any environment variables with matching names
  
      The num checks (eg PROM_DSN_1, PROM_DSN_2) go in order, so you can't do PROM_DSN_1, PROM_DSN_3,
      because it will fail on _2 and move on, so make sure your num dsns are in order (eg, 1, 2, 3, ...)
  
      example --
          export PROM_DSN_1=some.Interface://host:port/dbname#i1
          export PROM_DSN_2=some.Interface://host2:port/dbname2#i2
          $ python
          >>> import prom
          >>> print prom.interfaces # prints a dict with interfaces i1 and i2 keys
  
      :param dsn_env_name: string, the name of the environment variables
      """
      inters = []
      cs = dsnparse.parse_environs(dsn_env_name, parse_class=connection_class)
      for c in cs:
          inter = c.interface
          set_interface(inter, c.name)
          inters.append(inter)
  
      return inters