class IExternalCommandAvailability:
 """ An interface that should be implemented to provide the implementation for a accessibility check for a Revit add-in External Command. """
 def IsCommandAvailable(self,applicationData,selectedCategories):
  """
  IsCommandAvailable(self: IExternalCommandAvailability,applicationData: UIApplication,selectedCategories: CategorySet) -> bool

  

   Implement this method to provide control over whether your external command is 

    enabled or disabled.

  

  

   applicationData: An ApplicationServices.Application object which contains reference to 

    Application

  needed by external command.

  

   selectedCategories: An list of categories of the elements which have been selected in Revit in the 

    active document,

  or an empty set if no elements are selected or there is no 

    active document.

  

   Returns: Indicates whether Revit should enable or disable the corresponding external 

    command.
  """
  pass
 def __init__(self,*args):
  """ x.__init__(...) initializes x; see x.__class__.__doc__ for signaturex.__init__(...) initializes x; see x.__class__.__doc__ for signature """
  pass
