Edit an existing file by replacing a specific block of text with new content. Use the read tool first to understand the current content of the file.

Usage:
- Make sure the old_content is a unique block of text within the file.
- Include enough context in the old_content to ensure uniqueness.
- If adding new content, include context around the new content to ensure uniqueness and to specify the location of the new content in the file.
- If removing, new content should be empty.