[pre-commit.ci] auto fixes from pre-commit.com hooks

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Author: pre-commit-ci[bot]

data_structures/stacks/next_greater_element.py

@@ -6,6 +6,7 @@
 right side of x in the array. If no such element exists, output -1.
 """
 
+
 def next_greater_elements(arr):
     stack = []
     result = [-1] * len(arr)