Added length unit conversions
diff --git a/conversions/length_conversions.py b/conversions/length_conversions.py
new file mode 100644
index 000000000000..811a9a916b70
--- /dev/null
+++ b/conversions/length_conversions.py
@@ -0,0 +1,108 @@
+"""
+Conversion of length units.
+Available Units:- Metre,Kilometre,Feet,Inch,Centimeter,Yard,Foot,Mile,Millimeter
+
+USAGE :
+-> Import this file into their respective project.
+-> Use the function length_conversion() for conversion of length units.
+-> Parameters :
+    -> value : The number of from units you want to convert
+    -> from_type : From which type you want to convert
+    -> to_type : To which type you want to convert
+
+REFERENCES :
+-> Wikipedia reference: https://en.wikipedia.org/wiki/Meter
+-> Wikipedia reference: https://en.wikipedia.org/wiki/Kilometer
+-> Wikipedia reference: https://en.wikipedia.org/wiki/Feet
+-> Wikipedia reference: https://en.wikipedia.org/wiki/Inch
+-> Wikipedia reference: https://en.wikipedia.org/wiki/Centimeter
+-> Wikipedia reference: https://en.wikipedia.org/wiki/Yard
+-> Wikipedia reference: https://en.wikipedia.org/wiki/Foot
+-> Wikipedia reference: https://en.wikipedia.org/wiki/Mile
+-> Wikipedia reference: https://en.wikipedia.org/wiki/Millimeter
+"""
+
+from collections import namedtuple
+
+from_to = namedtuple("from_to", "from_ to")
+
+METRIC_CONVERSION = {
+    "meter": from_to(1, 1),
+    "kilometer": from_to(1000, 0.001),
+    "feet": from_to(0.3048, 3.28084),
+    "inch": from_to(0.0254, 39.3701),
+    "centimeter": from_to(0.01, 100),
+    "yard": from_to(0.9144, 1.09361),
+    "foot": from_to(0.3048, 3.28084),
+    "mile": from_to(1609.34, 0.000621371),
+    "millimeter": from_to(0.001, 1000),
+}
+
+
+def length_conversion(value: float, from_type: str, to_type: str) -> float:
+    """
+    Conversion between length units.
+
+    >>> length_conversion(4, "meter", "feet")
+    13.12336
+    >>> length_conversion(1, "meter", "kilometer")
+    0.001
+    >>> length_conversion(1, "kilometer", "inch")
+    39370.1
+    >>> length_conversion(3, "kilometer", "mile")
+    1.8641130000000001
+    >>> length_conversion(2, "feet", "meter")
+    0.6096
+    >>> length_conversion(4, "feet", "yard")
+    1.333329312
+    >>> length_conversion(1, "inch", "meter")
+    0.0254
+    >>> length_conversion(2, "inch", "mile")
+    3.15656468e-05
+    >>> length_conversion(2, "centimeter", "millimeter")
+    20.0
+    >>> length_conversion(2, "centimeter", "yard")
+    0.0218722
+    >>> length_conversion(4, "yard", "meter")
+    3.6576
+    >>> length_conversion(4, "yard", "kilometer")
+    0.0036576
+    >>> length_conversion(3, "foot", "meter")
+    0.9144000000000001
+    >>> length_conversion(3, "foot", "inch")
+    36.00001944
+    >>> length_conversion(4, "mile", "kilometer")
+    6.43736
+    >>> length_conversion(2, "mile", "inch")
+    126719.753468
+    >>> length_conversion(3, "millimeter", "centimeter")
+    0.3
+    >>> length_conversion(3, "millimeter", "inch")
+    0.1181103
+    >>> length_conversion(4, "wrongUnit", "inch")
+    Traceback (most recent call last):
+      File "/usr/lib/python3.8/doctest.py", line 1336, in __run
+        exec(compile(example.source, filename, "single",
+      File "<doctest __main__.length_conversion[18]>", line 1, in <module>
+        length_conversion(4, "wrongUnit", "inch")
+      File "<string>", line 85, in length_conversion
+    ValueError: Invalid 'from_type' value: 'wrongUnit'  Supported values are:
+    meter, kilometer, feet, inch, centimeter, yard, foot, mile, millimeter
+    """
+    if from_type not in METRIC_CONVERSION:
+        raise ValueError(
+            f"Invalid 'from_type' value: {from_type!r}  Supported values are:\n"
+            + ", ".join(METRIC_CONVERSION)
+        )
+    if to_type not in METRIC_CONVERSION:
+        raise ValueError(
+            f"Invalid 'to_type' value: {to_type!r}.  Supported values are:\n"
+            + ", ".join(METRIC_CONVERSION)
+        )
+    return value * METRIC_CONVERSION[from_type].from_ * METRIC_CONVERSION[to_type].to
+
+
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod()

Conversion of length units were added with respective tests being implemented and passed.
Available Units:- Metre,Kilometre,Feet,Inch,Centimeter,Yard,Foot,Mile,Millimeter

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