to_condensed_em_notation

to_condensed_em_notation(g, separator=',')

Return condensed EM notation for diagrams with single-letter node labels.

Constraints:

• Nodes must be sortable and of the same type (e.g., all strings or all ints).

• At most 52 nodes (a–zA–Z).

Parameters:

• g (PlanarDiagram) – Diagram to serialize.

• separator (str) – Token separator (default: comma).

Returns:

str – Condensed EM string (alphabetical node order).

Raises:

• ValueError – If node count exceeds 52.

• TypeError – If nodes are not mutually comparable for sorting.

Return type:

str