execute hello world with flask "ImportError: No module named flask" : <p>I'm trying to use flask and python. I did a simple file named <code>hello.py</code>. tHis file contains this code:</p>

<pre><code>from flask import Flask
app = Flask(__name__)


@app.route("/")
def main():
    return "Welcome!"

if __name__ == "__main__":
    app.run()
</code></pre>

<p>This is a simple hello world with flask. I want to execute it but actually, I have a problem. In the terminal, I typed <code>python hello.py</code> 
and I get this error:</p>

<pre><code>File "hello.py", line 1, in &lt;module&gt;
from flask import Flask
ImportError: No module named flask
</code></pre>

<p>Even that I installed flask globally.
I understand that this is a basic question, but I'm stuck?</p>
