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Python | Convert a nested list into a flat list
• Difficulty Level : Medium
• Last Updated : 10 Sep, 2018

The task is to convert a nested list into a single list in python i.e no matter how many levels of nesting is there in python list, all the nested has to be removed in order to convert it to a single containing all the values of all the lists inside the outermost brackets but without any brackets inside.

Examples:

Input : l = [1, 2, [3, 4, [5, 6] ], 7, 8, [9, [10] ] ]
Output : l = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

Input : l = [[[‘item1’, ‘item2’]], [[‘item3’, ‘item4’]]]
Output : l = [‘item1’, ‘item2’, ‘itm3, ‘item4”]

## Recommended: Please try your approach on {IDE} first, before moving on to the solution.

We use recursion because the levels of nesting cannot be predetermined.

 `# Python code to flat a nested list with``# multiple levels of nesting allowed.`` ` `# input list``l ``=` `[``1``, ``2``, [``3``, ``4``, [``5``, ``6``]], ``7``, ``8``, [``9``, [``10``]]]`` ` `# output list``output ``=` `[]`` ` `# function used for removing nested ``# lists in python. ``def` `reemovNestings(l):``    ``for` `i ``in` `l:``        ``if` `type``(i) ``=``=` `list``:``            ``reemovNestings(i)``        ``else``:``            ``output.append(i)`` ` `# Driver code``print` `(``'The original list: '``, l)``reemovNestings(l)``print` `(``'The list after removing nesting: '``, output)`
Output:
```The original list:  [1, 2, [3, 4, [5, 6]], 7, 8, [9, [10]]]
The list after removing nesting:  [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
```

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