sympify reads a string into an expression. Create expr.txt if it is not attached.

Goal

Factor the polynomial in expr.txt.

from pathlib import Path
Path('expr.txt').write_text('x**2 - 5*x + 6\n', encoding='utf-8')
print(Path('expr.txt').read_text(encoding='utf-8'))

from pathlib import Path
import sympy as sp
raw = Path('expr.txt').read_text(encoding='utf-8').strip()
e = sp.sympify(raw)
print(e)
print(sp.factor(e))

import sympy as sp
print(sp.sympify('sin(x)').subs(sp.symbols('x'), sp.pi / 2))

import sympy as sp
try:
    sp.sympify('not an expr !!!')
except Exception as err:
    print(type(err).__name__)