### Tell us what’s happening:

My question is concerning the “answer” code given after the previous step. It is located on the last line in the “Equation.**str**(self)” method.

I saw that the "strip(‘+’) was called twice. Is this simply a typo?

### Your code so far

```
from abc import ABC, abstractmethod
class Equation(ABC):
degree: int
def __init__(self, *args):
if (self.degree + 1) != len(args):
raise TypeError(
f"'Equation' object takes {self.degree + 1} positional arguments but {len(args)} were given"
)
if any(not isinstance(arg, (int, float)) for arg in args):
raise TypeError("Coefficients must be of type 'int' or 'float'")
if args[0] == 0:
raise ValueError("Highest degree coefficient must be different from zero")
self.coefficients = {(len(args) - n - 1): arg for n, arg in enumerate(args)}
def __init_subclass__(cls):
if not hasattr(cls, "degree"):
raise AttributeError(
f"Cannot create '{cls.__name__}' class: missing required attribute 'degree'"
)
def __str__(self):
terms = []
for n, coefficient in self.coefficients.items():
if not coefficient:
continue
if n == 0:
terms.append(f'{coefficient:+}')
elif n == 1:
terms.append(f'{coefficient:+}x')
equation_string = ' '.join(terms) + ' = 0'
return equation_string.strip('+').strip('+')
@abstractmethod
def solve(self):
pass
@abstractmethod
def analyze(self):
pass
class LinearEquation(Equation):
degree = 1
# User Editable Region
def solve(self):
pass
# User Editable Region
def analyze(self):
pass
lin_eq = LinearEquation(2, 3)
print(lin_eq)
```

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### Challenge Information:

Learn Interfaces by Building an Equation Solver - Step 25