%  java PartialCalculator

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Value of 1+2 is 3.0

PARSE TREE:

expression
   expression
      'NUMBER'(1.0)
   '+'
   expression
      'NUMBER'(2.0)

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Defining pi as 3.142857142857143

PARSE TREE:

definition
   'IDENTIFIER'(pi)
   '='
   expression
      expression
         'NUMBER'(22.0)
      '/'
      expression
         'NUMBER'(7.0)

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Twice this pi is 6.285714285714286

PARSE TREE:

expression
   expression
      'NUMBER'(2.0)
   '*'
   expression
      'IDENTIFIER'(pi)

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