old_contents: 'use strict';
  
  const fields = [
    'tags',
    'tags_vision',
    'tags_verified'
  ]
  
  module.exports = metadata => {
    fields.forEach(field => {
      const value = metadata[field];
      if(typeof(value) === 'string' && value !== '') {
        metadata[field] = value.split(',');
      } else {
        metadata[field] = [];
      }
    });
    return metadata;
  };
  
new_contents: 'use strict';
  
  const fields = [
    'tags',
    'tags_verified'
  ]
  
  module.exports = metadata => {
    fields.forEach(field => {
      const value = metadata[field];
      if(typeof(value) === 'string' && value !== '') {
        metadata[field] = value.split(',');
      } else {
        metadata[field] = [];
      }
    });
    return metadata;
  };
  
subject: Remove tags_vision field from splitting of tags -- as it is empty it will have no effect