fn fetch(&self, cmd: &str, custom_url: &Option<String>) -> Result<String> {
        self._fetch(cmd, custom_url)
    }
Fetches the command page from the provider.

# Parameters

- `cmd`: The name of the command for which the page should be fetched.
- `custom_url`: Optional parameter that, if supplied, specifies a custom URL from which to fetch the command page.

# Returns

This method returns a Result type. On successful fetch, it contains a `String` with the content of the fetched page.
In case of failure, it contains an error that provides further details about the issue encountered during the fetch operation.

# Errors

This method will return an error if the fetch operation fails.
src/helper/docs/mod.rs