title: How to reference variable dynamically in Python?
body: <p>I have the following code:</p>
  
  <pre><code>PROJECT_ID = 'test'
  BQ_TABLE_NAME_CATEGORIES = 'categories'
  BQ_TABLE_NAME_MANUFACTURERS = 'manufacturers'
  list = [BQ_TABLE_NAME_CATEGORIES, BQ_TABLE_NAME_MANUFACTURERS]
  table_categories = PROJECT_ID + '.'  + BQ_TABLE_NAME_CATEGORIES
  table_manufacturers = PROJECT_ID + '.' + BQ_TABLE_NAME_MANUFACTURERS
  
  for table in list:
      ....
      source_objects=['table_{0}'.format(table)]  #reference to the correct var
      ....
  </code></pre>
  
  <p>This however puts string inside <code>source_objects</code>. I want it to reference the variables (whatever is saved in the variables)
  meaning what I actually want is <strong>equivalent</strong> of this:</p>
  
  <p>When <code>table = BQ_TABLE_NAME_CATEGORIES</code> </p>
  
  <pre><code>source_objects = [ table_categories ] 
  </code></pre>
  
  <p>When <code>table = BQ_TABLE_NAME_MANUFACTURERS</code> </p>
  
  <pre><code>source_objects = [ table_manufacturers ] 
  </code></pre>