for readers familiar with other programming languagesthe semantics of python identifier is most similar to reference variable in java or pointer variable in +each identifier is implicitly associated with the memory address of the object to which it refers python identifier may be assigned to special object named noneserving similar purpose to null reference in java or +unlike java and ++python is dynamically typed languageas there is no advance declaration associating an identifier with particular data type an identifier can be associated with any type of objectand it can later be reassigned to another object of the same (or differenttype although an identifier has no declared typethe object to which it refers has definite type in our first examplethe characters are recognized as floating-point literaland thus the identifier temperature is associated with an instance of the float class having that value programmer can establish an alias by assigning second identifier to an existing object continuing with our earlier examplefigure portrays the result of subsequent assignmentoriginal temperature float temperature original figure identifiers temperature and original are aliases for the same object once an alias has been establishedeither name can be used to access the underlying object if that object supports behaviors that affect its statechanges enacted through one alias will be apparent when using the other alias (because they refer to the same objecthoweverif one of the names is reassigned to new value using subsequent assignment statementthat does not affect the aliased objectrather it breaks the alias continuing with our concrete examplewe consider the commandtemperature temperature the execution of this command begins with the evaluation of the expression on the right-hand side of the operator that expressiontemperature is evaluated based on the existing binding of the name temperatureand so the result has value that is that result is stored as new floating-point instanceand only then is the name on the left-hand side of the assignment statementtemperature(re)assigned to the result the subsequent configuration is diagrammed in figure of particular notethis last command had no effect on the value of the existing float instance that identifier original continues to reference float float temperature original figure the temperature identifier has been assigned to new valuewhile original continues to refer to the previously existing value