code: def apply(self, **kwexpr):
          
          for alias, expr in kwexpr.items():
              self._projections.append([alias, expr])
  
          return self
docs: Specify one or more projection expressions to add to each result
  
          ### Parameters
  
          - **kwexpr**: One or more key-value pairs for a projection. The key is
              the alias for the projection, and the value is the projection
              expression itself, for example `apply(square_root="sqrt(@foo)")`