In recent work on a Subgraph().conclude() method, which is modeled on the SubsetEq().conclude() method, an interesting error (and sequence of further errors) arose when tryingSubsetEq().prove() (and later, SubsetEq().conclude()) as shown below:

The offending block of code appears to be:

with an initial error message being

TypeError: __init__() missing 1 required keyword-only argument: 'styles'

in calling Operation() on line 99. Attempts to temporarily correct this lead to error messages about not using Operation directly, and then complaints about the relabel_map on line 103 if we try Function() in place of Operation, etc.