[Python] Cálculos aritméticos (soma) no banco de dados Flask-SQLAlchemy

Tenho uma tabela no meu banco de dados que o usuário coloca o total de horas de voo que ele fez. Queria saber como faço para somar todas as horas do usuário que está no banco de dados e mostrar no templates.



Backend:

from flask import Flask, render_template, flash, redirect, url_for
from flask_sqlalchemy import SQLAlchemy
from flask_wtf import FlaskForm
from wtforms import StringField
from wtforms.validators import DataRequired

app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///database.db'
db = SQLAlchemy(app)
app.config['SECRET_KEY'] = 'askdjrw83845gkdksjs1234jdjsyqerdsdfkgji9547djfh4'

class MyForm(FlaskForm):
username = StringField('Nome', validators=[DataRequired()])
horas = StringField('Horas de Voo', validators=[DataRequired()])

class Horas(db.Model):
id = db.Column(db.Integer, primary_key=True)
username = db.Column(db.String(120))
hora = db.Column(db.String(10))

db.create_all()

@app.route('/', methods=['GET', 'POST'])
def index():
posts = Horas.query.all()
form = MyForm()
if form.validate_on_submit():
post = Horas(username=form.username.data, hora=form.horas.data)
db.session.add(post)
db.session.commit()
flash("valor Registrador")
return redirect(url_for('index'))
return render_template('index.html', form=form, posts=posts)

if __name__ == '__main__':
app.run(host='0.0.0.0', port='3000')


Frontend:

<html>
<head>
<style>
table {
font-family: arial, sans-serif;
border-collapse: collapse;
width: 100%;
}

td, th {
border: 1px solid #dddddd;
text-align: left;
padding: 8px;
}

tr:nth-child(even) {
background-color: #dddddd;
}
</style>
<
</head>
<body>
<form method="POST" action="/">
{{ form.hidden_tag() }}
<p>{{ form.username.label }} {{ form.username(size=20) }}</p>
<p>{{ form.horas.label }} {{ form.horas(size=5) }}</p>
<input type="submit" value="Enviar">
</form>
<hr>
<br>
<table>
<tr>
<th>Nome</th>
<th>Horas</th>
</tr>
{% for posts in posts %}
<tr>
<td>{{ posts.username }}</td>
<td>{{ posts.hora }}</td>
</tr>

{% endfor %}

</body>

</html>

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