def clean_key_name(self):
key = self.cleaned_data['<STR_LIT>']<EOL>if not key.startswith(self.get_key_prefix()):<EOL><INDENT>raise forms.ValidationError('<STR_LIT>')<EOL><DEDENT>if not self.get_upload_key():<EOL><INDENT>raise forms.ValidationError('<STR_LIT>')<EOL><DEDENT>return key<EOL>
Validates that the key in the provided data starts with the
        required prefix, and that it exists in the bucket.