Here is the design of a clinical trial:

Official Title: Just Kwit: Mobile Intervention for Tobacco Cessation

Included conditions:
- Smoking Cessation

Study Armgroups:
- {'label': 'Kwit app', 'type': 'EXPERIMENTAL', 'description': 'Use of Kwit smartphone app', 'interventionNames': ['Other: Kwit smartphone app']}
- {'label': 'Standard of care', 'type': 'NO_INTERVENTION', 'description': 'Patient initiated follow-up post discharge'}

Interventions:
- {'type': 'OTHER', 'name': 'Kwit smartphone app', 'description': 'Kwit smarphone app', 'armGroupLabels': ['Kwit app']}

Primary Outcomes:
- {'measure': 'Feasibility - Helpfulness and Ease of Use of the Intervention Smartphone App', 'description': 'Assessment of feasibility - Descriptive statistics that will be obtained via a follow up survey will be used to assess feasibility. The follow up survey will be administered one month after discharge via email, phone or in-person, determined by the preference of the participant. Specific questions will be asked asking participants to rate the Kwit smartphone application based on helpfulness, ease of use, and to list frustrations and helpful aspects of the application.\n\nHow helpful was the Kwit app? Very helpful Somewhat helpful Neutral Not very helpful Not at all helpful\n\nWas the app easy to use? Very Somewhat Neutral Not much Not at all\n\nWas it frustrating to use? Very Somewhat Neutral Not much Not at all\n\nWhat, if anything, was helpful about the app? What, if anything, was not helpful about the app?', 'timeFrame': '1-month'}
- {'measure': 'Feasibility - Frequency of Use', 'description': 'Assessment of feasibility - Descriptive statistics that will be obtained via a follow up survey will be used to assess feasibility. The follow up survey will be administered one month after discharge via email, phone or in-person, determined by the preference of the participant. Specific questions will be asked asking participants to rate the Kwit smartphone application based on frequency of use.', 'timeFrame': '1-month'}

Please estimate the sample size based on the assumption: 
Not explicitly stated; formal sample size calculation is not appropriate.
Sample size
        Given this is a feasibility trial, a formal sample size calculation is not appropriate [17]. For the current study, we are informed by quantitative usability-testing recommendations that suggest a sample size of 20 [19]. Because we wish to stratify by birth sex, we obtained our sample size of 40 individuals. While we expect this to be more than sufficient, we will remain flexible in our approach and will recruit additional individuals if necessary.