input: Write a function to summarize customer purchase data from a CSV file.
  assert summarize_customer_data('customer_data.csv') == {
      '123': {'purchase_category': {'electronics', 'books'}, 'total_amount': 150.75},
      '456': {'purchase_category': {'clothing'}, 'total_amount': 75.50},
      '789': {'purchase_category': {'groceries', 'electronics'}, 'total_amount': 200.00}
  }
  assert summarize_customer_data('empty_data.csv') == {}
  assert summarize_customer_data('single_customer.csv') == {
      '001': {'purchase_category': {'toys'}, 'total_amount': 50.00}
  }
output: import csv
  
  def summarize_customer_data(file_path):
      customer_summary = {}
      
      with open(file_path, newline='') as csvfile:
          csvreader = csv.DictReader(csvfile)
          
          for row in csvreader:
              customer_id = row['customer_id']
              category = row['purchase_category']
              amount = float(row['amount'])
              
              if customer_id not in customer_summary:
                  customer_summary[customer_id] = {'purchase_category': set(), 'total_amount': 0.0}
              
              customer_summary[customer_id]['purchase_category'].add(category)
              customer_summary[customer_id]['total_amount'] += amount
      
      return customer_summary