Python: Fix wrong use of OpenAI prompt priming and problem (#901)

This PR fixes the wrong use of OpenAI prompt priming and problem role
for Python projects, following #899 and #900.

---------

Signed-off-by: Arthur Chan <[email protected]>

Author: arthurscchan

llm_toolkit/prompt_builder.py

@@ -1345,8 +1345,8 @@ def __init__(self,
         self.benchmark.project)
 
     # Load templates.
-    self.base_template_file = self._find_template(template_dir,
-                                                  'python_base.txt')
+    self.priming_template_file = self._find_template(template_dir,
+                                                     'python_priming.txt')
     self.problem_template_file = self._find_template(template_dir,
                                                      'python_problem.txt')
 
@@ -1389,18 +1389,17 @@ def _format_target(self, signature: str) -> str:
 
   def _format_problem(self, signature: str) -> str:
     """Formats a problem based on the prompt template."""
-    base = self._get_template(self.base_template_file)
-    target_str = self._format_target(signature)
+    problem = self._format_target(signature)
 
-    problem = base + target_str
-    problem = problem.replace("{PROJECT_NAME}", self.benchmark.project)
-    problem = problem.replace("{PROJECT_URL}", self.project_url)
+    problem = problem.replace('{PROJECT_NAME}', self.benchmark.project)
+    problem = problem.replace('{PROJECT_URL}', self.project_url)
 
     return problem
 
   def _prepare_prompt(self, prompt_str: str):
     """Constructs a prompt using the parameters and saves it."""
-    self._prompt.add_priming(prompt_str)
+    self._prompt.add_priming(self._get_template(self.priming_template_file))
+    self._prompt.add_problem(prompt_str)
 
   def build(self,
             example_pair: list[list[str]],