old_contents: """Store version constants."""
  MAJOR_VERSION = 0
  MINOR_VERSION = 15
  PATCH_VERSION = '0'
  __version__ = '{}.{}.{}'.format(MAJOR_VERSION, MINOR_VERSION, PATCH_VERSION)
  
new_contents: """Store version constants."""
  MAJOR_VERSION = 0
  MINOR_VERSION = 16
  PATCH_VERSION = '0.dev0'
  __version__ = '{}.{}.{}'.format(MAJOR_VERSION, MINOR_VERSION, PATCH_VERSION)
  
subject: Bump version to 0.16.0.dev0