sagemathgh-39366: Add documentation to LaurentSeries point to accessors
    
I feel it's originally too undiscoverable. Since `f` and `n` are
explicitly mentioned in the documentation I think it's a good idea to
mention how to access it programmatically.

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URL: sagemath#39366
Reported by: user202729
Reviewer(s): Kwankyu Lee

Author: Release Manager

src/sage/rings/laurent_series_ring_element.pyx

@@ -1,6 +1,12 @@
-"""
+r"""
 Laurent Series
 
+Laurent series in Sage are represented internally as a power of the variable
+times the power series part. If a Laurent series `f` is represented as
+`f = t^n \cdot u` where `t` is the variable and `u` has nonzero constant term,
+`u` can be accessed through :meth:`~LaurentSeries.valuation_zero_part` and `n`
+can be accessed through :meth:`~LaurentSeries.valuation`.
+
 EXAMPLES::
 
     sage: R.<t> = LaurentSeriesRing(GF(7), 't'); R
@@ -35,11 +41,6 @@ Saving and loading.
     sage: loads(K.dumps()) == K                                                         # needs sage.rings.real_mpfr
     True
 
-IMPLEMENTATION: Laurent series in Sage are represented internally
-as a power of the variable times the unit part (which need not be a
-unit - it's a polynomial with nonzero constant term). The zero
-Laurent series has unit part 0.
-
 AUTHORS:
 
 - William Stein: original version
@@ -89,8 +90,8 @@ cdef class LaurentSeries(AlgebraElement):
     r"""
     A Laurent Series.
 
-    We consider a Laurent series of the form `t^n \cdot f` where `f` is a
-    power series.
+    We consider a Laurent series of the form `f = t^n \cdot u` where `u` is a
+    power series with nonzero constant term.
 
     INPUT:
 
@@ -1301,7 +1302,7 @@ cdef class LaurentSeries(AlgebraElement):
             sage: g.valuation()
             0
 
-        Note that the valuation of an element undistinguishable from
+        Note that the valuation of an element indistinguishable from
         zero is infinite::
 
             sage: h = f - f; h