old_contents: """Application core."""
  
  from flask.ext.mail import Mail
  from flask.ext.migrate import Migrate
  from flask.ext.security import Security
  from flask.ext.sqlalchemy import SQLAlchemy
  
  __all__ = ('db',)
  
  db = SQLAlchemy()
  mail = Mail()
  migrate = Migrate()
  security = Security()
  
new_contents: """Application core."""
  
  from flask.ext.mail import Mail
  from flask.ext.migrate import Migrate
  from flask.ext.security import Security
  from flask.ext.sqlalchemy import SQLAlchemy
  
  __all__ = ('db',)
  
  db = SQLAlchemy()
  # NOTE: It would be cleaner to simply pass in a MetaData object to SQLAlchemy.
  # Flask-SQLAlchemy supports this starting with version 2.1, which is not out at
  # the time of this writing.
  db.metadata.naming_convention = {
      'ix': 'ix_%(column_0_label)s',
      'uq': '%(table_name)s_%(column_0_name)s_key',
      'ck': 'ck_%(table_name)s_%(constraint_name)s',
      'fk': '%(table_name)s_%(column_0_name)s_fkey',
      'pk': '%(table_name)s_pkey',
  }
  mail = Mail()
  migrate = Migrate()
  security = Security()
  
subject: Add SQLAlchemy naming conventions