MassBudgetInput:

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   Create a data structure for MassBudget. Enter parameter pairs.

   Type MassBudgetInput to see the data structure.

   This function will fill in any fields that are not entered.

   The param field is a data structure. It depends on type. 

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   Form:
   c = MassBudgetInput( varargin )
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   Inputs
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   varargin    (:)     Parameter pairs

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   Outputs
   -------
   c           (1,1)   MassBudget data structure

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