diff --git a/practice/isogram/isogram.py b/practice/isogram/isogram.py
index 98b31c5..157020e 100644
--- a/practice/isogram/isogram.py
+++ b/practice/isogram/isogram.py
@@ -1,2 +1,26 @@
 def is_isogram(string):
-    pass
+    """
+    Check if the input string is an isogram.
+
+    An isogram (also known as a "nonpattern word") is a word or phrase
+    without a repeating letter, however spaces and hyphens are allowed
+    to appear multiple times.
+
+    Args:
+        string (str): The string to check.
+
+    Returns:
+        bool: True if the string is an isogram, False otherwise.
+
+    Examples:
+        >>> is_isogram("subdermatoglyphic")
+        True
+        >>> is_isogram("Alphabet")
+        False
+    """
+    # Remove hyphens and spaces, and convert to lowercase
+    scrubbed = string.replace('-', '').replace(' ', '').lower()
+
+    # An isogram has no repeating letters, so the length of the string
+    # should be equal to the number of unique letters (the size of the set)
+    return len(scrubbed) == len(set(scrubbed))
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