docs: def parse_database_url(url):
      """Parses a database URL."""
  
      if url == 'sqlite://:memory:':
          # this is a special case, because if we pass this URL into
          # urlparse, urlparse will choke trying to interpret "memory"
          # as a port number
          return {
              'ENGINE': DATABASE_SCHEMES['sqlite'],
              'NAME': ':memory:'
          }
          # note: no other settings are required for sqlite
  
      # otherwise parse the url as normal
      config = {}
  
      url = urlparse.urlparse(url)
  
      # Remove query strings.
      path = url.path[1:]
      path = path.split('?', 2)[0]
  
      # if we are using sqlite and we have no path, then assume we
      # want an in-memory database (this is the behaviour of sqlalchemy)
      if url.scheme == 'sqlite' and path == '':
          path = ':memory:'
  
      # Update with environment configuration.
      config.update({
          'NAME': path or '',
          'USER': url.username or '',
          'PASSWORD': url.password or '',
          'HOST': url.hostname or '',
          'PORT': url.port or '',
      })
  
      if url.scheme in DATABASE_SCHEMES:
          config['ENGINE'] = DATABASE_SCHEMES[url.scheme]
  
      return config