:decimal_transform — removes Decimal value-transforming calls.

The family replaces a value-transforming Decimal call with its input, testing whether the transformation itself is observed:

Decimal.normalize(num)        # -> num
Decimal.apply_context(num)    # -> num
Decimal.abs(num)              # -> num
Decimal.negate(num)           # -> num
Decimal.sqrt(num)             # -> num
Decimal.round(num, places)    # -> num

In a pipe stage, the call becomes Elixir.Function.identity/1 so the surrounding pipe remains compile-safe.