  # Leading comment line spaces are
   # neither content nor indentation.
    
Not indented:
 By one space: |
    By four
      spaces
 Flow style: [    # Leading spaces
   By two,        # in flow style
  Also by two,    # are neither
# Tabs are not allowed:
#  	Still by two   # content nor
    Still by two   # content nor
    ]             # indentation.
