KeyError — Expert Examples

# Exception groups (Python 3.11+)
import sys
print(f"Python {sys.version}")

# Exception hierarchy inspection
print(f"KeyError MRO:")
for cls in KeyError.__mro__:
    print(f"  {cls.__name__}")

# Exception attributes
try:
    d = {}; d["missing"]
except KeyError as e:
    print(f"\nException attributes:")
    print(f"  args: {e.args}")
    print(f"  __traceback__: {type(e.__traceback__)}")

    # Traceback manipulation
    import traceback
    tb_lines = traceback.format_exception(type(e), e, e.__traceback__)
    print(f"  Traceback lines: {len(tb_lines)}")