import fitz

doc = fitz.open('myanmar_book.pdf')
text = ""
for i in range(10, 20):  # 0-indexed, so 10-19 are pages 11-20
    page = doc[i]
    text += f"\n\n--- Trang {i+1} ---\n\n"
    text += page.get_text()

with open('test_pymupdf.txt', 'w', encoding='utf-8') as f:
    f.write(text)