getFeatures-methods:  Get features (methods)
Description
 Methods for fetching a subset of features from a given data structure
Methods
 - x = "missing", y = "missing"
 -  Handle empty function call 
  - x = "ExpressionSet", y = "missing"
 -  Handle input of an object of class 
ExpressionSet. Select all feature data.   - x = "ExpressionSet", y = "NULL"
 -  Handle input of an object of class 
ExpressionSet. Select all feature data.   - x = "ExpressionSet", y = "vector"
 -  Handle input of an object of class 
ExpressionSet. Select a subset of features.   - x = "AnnotatedDataFrame", y = "missing"
 -  Handle input of an 
AnnotatedDataFrame object. Select all feature data.   - x = "AnnotatedDataFrame", y = "NULL"
 -  Handle input of an 
AnnotatedDataFrame object. Select all feature data.   - x = "AnnotatedDataFrame", y = "vector"
 -  Handle input of an 
AnnotatedDataFrame object. Select a subset of features.   - x = "vector", y = "missing"
 -  Handle input of a vector (interpreted as a matrix). Select all feature data 
  - x = "vector", y = "NULL"
 -  Handle input of a vector (interpreted as a matrix). Select all feature data 
  - x = "vector", y = "vector"
 -  Handle input of two vectors specifying feature data and feature subset information, respectively. 
  - x = "matrix", y = "vector"
 -  Handle input of a matrix and a vector specifying feature data and feature subset information, respectively.