   Attention: the data frames do not match exactly, but as no primary key columns are
   provided, the row and column matches cannot be computed.

 Schemas
 ▔▔▔▔▔▔▔
   ┏━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━┓
   ┃  Left only   ┃  In common   ┃
   ┃  2 columns   ┃   1 column   ┃
   ┡━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━┩
   │ col_a [Null] │     ...      │
   │ col_b [Null] │              │
   └──────────────┴──────────────┘
