Changes in version 0.3 (2020-06-16)                   

  - Added get.preexisting function to the API.

                  Changes in version 0.2 (2019-08-28)                   

  - Added functions: get.stdout.nodes, get.args, get.val.type,
    get.tool.info
  - Snapshot nodes include path to the snapshot file

                 Changes in version 0.1.2 (2019-06-13)                  

  - Added functions: get.urls, get.error.nodes, and get.variable.named
  - Added only.files parameter to get.input.files.
  - Fixed bug in the parsing of sourced scripts
  - Changed the getter functions so that when they return an empty data
    frame, it still has column names
  - Export ProvInfo class

                 Changes in version 0.1.1 (2018-12-27)                  

  - Updated to correspond to the current JSON Prov format