MF004: empty-cells

✨ Formatting ⚠️ Unsafe Fixable

MF004: Empty cells that can be safely removed.

What it does

Detects cells that contain only:

• Whitespace characters (spaces, tabs, newlines)
• Comments (lines starting with #)
• Pass statements (pass)
• Any combination of the above

Why is this bad?

Empty cells can:

• Create clutter in notebook structure
• Add unnecessary complexity to the execution graph
• Make notebooks harder to read and maintain
• Increase file size without adding value

While not functionally breaking, removing empty cells improves code clarity and reduces visual noise.

Examples

Problematic:

# Cell 1: Only whitespace

Problematic:

# Cell 2: Only comments
# This is just a comment
# Nothing else here

Problematic:

# Cell 3: Only pass statement
pass

Problematic:

# Cell 4: Mix of comments, whitespace, and pass
# Some comment

pass
# Another comment

Note: This fix requires --unsafe-fixes because removing cells changes the notebook structure, and potentially removes user-intended content.

References

• Understanding Errors
• Best Practices