anchor.diff:  Returns the unique *id* of the lock.
   
   
  -=== Instance methods
  -
  -==== $lock->grantGroupKey(Group $group) : void
  -
  -Registers '$group' as having a \'key' to this lock in the 'locks_group_keys' table of the database.
  -This allows the group to be verified with *checkGroupKey()* (and its members to be verified with *checkUserKey()*).
  -
  -
  -==== $lock->checkGroupKey(Group $group) : bool
  -
  -Returns *true* if '$group' is registered as having a \'key' to this lock in the 'locks_group_keys' table in the database, otherwise *false*.
  -
  -
  -==== $lock->revokeGroupKey(Group $group) : void
  -
  -Removes the \'key' for this lock registered for '$group' in the 'locks_group_keys' table in the database (if one exists).
  -
  -
  -==== $lock->grantUserKey(User $user) : void
  -
  -Registers '$user' as having a \'key' to this lock in the 'locks_user_keys' table of the database.
  -This allows the user to be verified with *checkUserKey()*.
  -
  -
  -==== $lock->checkUserKey(User $user, bool $checkGroups = true) : bool
  -
  -Returns *true* if '$user' is registered as having a \'key' to this lock in the 'locks_user_keys' table in the database.
  -Additionally returns *true* if '$checkGroups' is set to *true* and any of the groups the user is a member of are registered as having a key in the 'locks_group_keys' table.
  -Returns *false* otherwise.
  -
  -
  -==== $lock->revokeUserKey(User $user) : void
  -
  -Removes the \'key' for this lock registered for '$user' in the 'locks_user_keys' table in the database (if one exists).
  -
  -
  -==== $lock->remove() : void
  -
  -Removes the lock from the database.
  -
  -
  -=== Static methods
  +=== Lock Management
   
   ==== __construct(int $id)
   
  
positive.code: 
  Returns a *Lock* representing the lock referenced by '$id', or *NULL* if no lock with that id found.
  
  
  ==== Lock::setupDB() : void
  
  
negative.code: for more details.
  
  
  ==== $lock->remove() : void
  
  Removes the lock from the database.
  
  
  ==== Lock::getAll() : array
  
  Returns an array of *Lock* objects representing all locks in the database.
  